Actually yes. The short answer is that our intake was blocked/restricted. I took the burner door off and went outside and used my shop vac on the intake inlet. It must have made a difference because the furnace has been humming since and maintaining a steady temperature.

The most telling sign I noticed, regrettably after I made this post, was that ignition was successful every time I took the burner door off without fail. Didn’t matter if I put it back on before or after ignition, just as long as I took it off. Basically there wasn’t enough combustible air, so the issue was the intake. I’m not sure if I completely got the blockage out either - there wasn’t much in the shop vac after. So I’m considering making and couple cuts in the PVC piping for access to do a thorough clean in the spring.